[CVE-2011-1746] agp: fix OOM and buffer overflow

[Andy Whitcroft]

CVE-2011-1746
	Multiple integer overflows in the (1) agp_allocate_memory and (2)
	agp_create_user_memory functions in drivers/char/agp/generic.c
	in the Linux kernel before 2.6.38.5 allow local users to trigger
	buffer overflows, and consequently cause a denial of service
	(system crash) or possibly have unspecified other impact, via
	vectors related to calls that specify a large number of memory
	pages.

This fix was applied to Oneiric, Natty, and Lucid via mainline and
stable updates.  Following this email is a patch which applies to both
Hardy and Maverick, this is a simple cherry-pick from mainline.

Proposing for Hardy and Maverick.

-apw